Ladder-type filters including piezoelectric thin film resonators have been used as filters and duplexers for wireless devices such as, for example, mobile phones. In the piezoelectric thin film resonator, a lower electrode, a piezoelectric film, and an upper electrode are stacked on a substrate. The region where the lower electrode and the upper electrode face each other across at least a part of the piezoelectric film is a resonance region. It has been known to insert an insertion film between the lower electrode and the upper electrode in the outer peripheral region within the resonance region and not to insert the insertion film in the center region of the resonance region as disclosed in, for example, Japanese Patent Application Publication Nos. 2015-95729, 2016-29766, and 2017-34358 (hereinafter, referred to as Patent Documents 1 through 3, respectively). It has been known to use the piezoelectric thin film resonator for the ladder-type filter as disclosed in, for example, Japanese Patent Application Publication Nos. 2003-22074, 2004-173236, 2005-223808, and 2007-324823 (hereinafter, referred to as Patent Documents 4 through 7, respectively).